Carbon dioxide, CO2 gas, is mixed with beverage, such as water or flavoured water, to produce a carbonated beverage. The CO2 gas dissolves at least partially in the water and forms carbonic acid, H2CO3. The CO2 is weakly soluble in water, therefore it separates back into CO2 gas, which form the bubbles consumers associate with carbonated beverages.
CO2 gas may be mixed into water in different ways utilizing two physical principles, mixing under high pressure or mixing over a long period of time or a combination thereof. Water pressure and water temperature affect the solubility of CO2 gas in water. Cold water will dissolve more CO2 than warm water.
For in-line carbonation, i.e. when flowing beverage is to be carbonated, both pressure and time is limited. Furthermore, water temperature may vary, e.g. during different times of the year. Water pressure may also vary. If not properly adjusted for current operating conditions, an in-line carbonator may easily provide either badly carbonated beverage or a stream of CO2 gas with occasional slugs of beverage. It is thus a challenge to produce an in-line carbonator which will provide carbonated beverage under different operating conditions.
EP 2070587 discloses a beverage dispenser provided with an in-line beverage carbonation system. The beverage dispenser comprises a liquid beverage supply line fluidly connected to a water source, a gas supply line fluidly connected to a pressurized gas source, and at least one mixing device for mixing the gas with the liquid beverage. At least one inlet port is fluidly connecting the gas supply line to the liquid beverage supply line, or to the mixing device, for introducing the gas into the liquid beverage. Liquid beverage mixed with gas is dispensed at a dispenser point.
U.S. Pat. No. 5,510,060 discloses an in-line carbonator comprising a casing defining an elongated chamber having a helical groove in an inner wall and an elongated inner body disposed in the chamber. The elongated inner body and the helical groove define a helical flow passage. At one end of the helical channel, liquid to be carbonated is supplied to the helical flow passage, and at the other end of the helical flow passage carbonated liquid exits the helical passage. The elongated inner body is formed of a micro-porous material. CO2 gas which carbonates the liquid diffuses via the micro-porous material into the liquid in the helical passage from an inner gas chamber of the inner body. In case of a pressure drop on the CO2 gas side or increase of pressure on the liquid side, liquid will penetrate into the micro-porous material. The micro pores will hold the liquid and it may be difficult under ordinary operating conditions to remove the liquid from all the micro pores. The operation conditions of the carbonator are negatively influenced when micro pores are filled with liquid.
IT PZ20080002 (A1) filed 2008 May 16 discloses an in-line mixing arrangement for liquid and gas. The arrangement comprises a tube with an inner diameter varying N-fold between at least two different inner diameters. In practice the arrangement does not provide a satisfying solution for in-line carbonation of a beverage.
Thus, there still exists a need for an in-line carbonator which at least is subjected to less of the problems associated with the known in-line carbonators.